http://blogs.msdn.com/jaimer/archive/2007/05/17/ishittestvisible-and-opacity-in-silverlight-1-0.aspxI spent last friday "fighting" this breaking change from earlier CTPs , so sharing hoping to save some one else time.. In earlier CTPs, UIements with Opacity = 0 were NOT hit testable... Now, they are [same behavior as WPF]... So if you have layered controlsen-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/jaimer/archive/2007/05/17/ishittestvisible-and-opacity-in-silverlight-1-0.aspx#2698696Thu, 17 May 2007 19:53:14 GMT91d46819-8472-40ad-a661-2c78acb4018c:2698696WynApse<p>Silverlight Cream for May 17, 2007</p>